Electrical Safety Lesson 7: GFCI & GFPE

Questions and Answers

What is the UL, LLC requirement for ground-fault circuit interrupters regarding tripping?

Tripping shall occur at 10 mA

Tripping shall occur at 6 mA (correct)

Tripping shall not trip at less than 4 mA (correct)

All of the above

Which of the following are common shock severity factors for humans? (Select all that apply)

Length of time (correct)

Path across the body (correct)

Size of the person (correct)

Amount of current (correct)

Frequency of the circuit (correct)

What is a device intended for the protection of personnel that functions to deenergize a circuit when a current to ground exceeds the values established for a Class A device?

Ground-fault circuit interrupter

Ground-fault circuit interrupter protection is available in which types of equipment or products? (Select all that apply)

Any of the above Signup and view all the answers

What is the operating imbalance threshold that a ground-fault circuit interrupter operates on?

4 to 6 mA Signup and view all the answers

Ground-fault circuit-interrupter protection is required for receptacles installed within how many feet of a sink in a dwelling unit? (Select all that apply)

All of the above Signup and view all the answers

In older existing installations without equipment grounding conductors at the outlets, which is acceptable for receptacle replacements? (Select all that apply)

Any of the above is acceptable. Signup and view all the answers

What provides a method for installing an equipment grounding conductor for receptacles that are being replaced at a location where one is desired but is not present?

Section 250.130(C) Signup and view all the answers

Where installed in dwelling unit kitchens, all 125-volt, single-phase, 15- and 20-ampere receptacles that are installed to serve what shall be GFCI protected? (Select all that apply)

Both A and B Signup and view all the answers

What contains the requirements for ground-fault protection for personnel using temporary power?

NEC 590.6 Signup and view all the answers

What is generally required for grounded electrical services and feeders of more than 150 volts to ground but not exceeding 1,000 volts phase-to-phase?

Ground-fault protection of equipment Signup and view all the answers

What is defined as a system intended to provide protection of equipment from damaging line-to-ground fault currents?

Ground-fault protection of equipment Signup and view all the answers

What does Section 230.95 require regarding ground-fault protection?

For each service disconnect rated 1,000 amperes or more. Signup and view all the answers

What is the maximum setting for ground-fault protection of equipment?

1,200 A Signup and view all the answers

What voltage and phase arrangement requires ground-fault protection of equipment?

480Y/277V, 3-phase, 4-wire, wye-connected Signup and view all the answers

To whom is a record of performance testing of ground-fault protection required to be made?

The authority having jurisdiction Signup and view all the answers

In health care facility power systems, the additional level of GFPE is not permitted on the load side of what?

Essential system transfer switch Signup and view all the answers

What does a zero-sequence-type GFPE typically consist of?

A current sensor, ground-fault relay, and a shunt-trip circuit breaker. Signup and view all the answers

What is the maximum time-delay for ground-fault currents that exceed 3,000 amperes?

1 second Signup and view all the answers

Which sections require ground-fault protection of equipment to be performance tested when first installed on site? (Select all that apply)

215.10 Signup and view all the answers

What is one significant difference between ground-fault circuit interrupters and ground-fault protection of equipment?

One provides protection for people, while the other provides protection for equipment. Signup and view all the answers

Which of the following is not a requirement of the NEC for GFPE installed in service equipment as part of a new construction project?

Push button testing can suffice Signup and view all the answers

In wet procedure locations of health care facilities, which type of protective equipment is required when GFCI protection cannot be installed?

Isolated power systems in accordance with 517.160 Signup and view all the answers

Study Notes

Ground-Fault Circuit Interrupters (GFCI)

Class A GFCIs trip when continuous 60-hertz differential current exceeds 6 mA and do not trip below 4 mA.
Common shock severity factors for humans include the amount of current, frequency, duration, body path, and person size.
GFCIs protect personnel by de-energizing circuits when current to ground exceeds specified Class A values.
GFCI protection is available in circuit breakers, cord sets, outlet devices, and plug-in adaptors.

GFCI Operation and Installation

GFCIs monitor supply and return current conductors for imbalances exceeding 4 to 6 mA.
GFCI protection is required for receptacles within 3, 5, or 6 feet of sinks in dwelling units.
Existing installations can replace non-grounding receptacles with GFCI devices, marked "No Equipment Ground," or replace with grounding-type receptacles through GFCI devices, marked accordingly.

Equipment Grounding Conductors

Section 250.130(C) allows for installing grounding conductors where none exist during receptacle replacements.
GFCI protection is mandated for receptacles serving countertop surfaces or within 6 feet of sink edges in kitchens.

Regulations and Standards

NEC 590.6 details ground-fault protection requirements for temporary power at construction sites.
Ground-fault protection of equipment is required for grounded electrical services over 150 volts to ground, not exceeding 1,000 volts phase-to-phase.
Service disconnects rated 1,000 A or more must comply with Section 230.95, requiring ground-fault protection.

Technical Specifications

Maximum setting for ground-fault protection of equipment is 1,200 A, with a one-second delay for currents over 3,000 A.
Voltage systems requiring protection include 480Y/277V, 3-phase, 4-wire, wye-connected configurations.
Performance testing of ground-fault protection equipment is mandatory upon installation, with records kept for the authority having jurisdiction.

Additional Context

Health care facilities must not place additional ground-fault protection on the load side of essential system transfer switches.
Neutral-ground strap type systems monitor ground-fault currents at the main bonding jumper.
Zero-sequence-type protection components include a current sensor around all conductors, a ground-fault relay, and a shunt-trip circuit breaker.

Key Differences Between GFCI and GFPE

GFCIs focus on providing protection to individuals, while ground-fault protection of equipment safeguards electrical devices.
Performance testing, while necessary for GFPE upon installation, can utilize push-button testing rather than primary injection testing as per NEC requirements.

Special Requirements in Healthcare

In critical areas where GFCIs cannot interrupt power, isolated power systems are mandated for patient safety, as specified in section 517.160.

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Description

Test your knowledge on Ground-Fault Circuit Interrupters (GFCI) and Ground-Fault Protection of Equipment (GFPE) through this set of flashcards. This lesson covers critical aspects like tripping requirements and shock severity factors relevant to electrical safety.